Technological Field
The present technology relates to an adjustable writing circuit, such as a write pulse driver, for writing to memory devices, and methods for manufacturing and operating such devices. Specifically, the present technology relates to an adjustable writing circuit for writing data to a bitline of a memory comprised of phase change materials, and methods for manufacturing and operating such devices.
Description of Related Art
In a phase change memory (PCM), each memory cell includes a phase change memory element. The phase change memory element can be caused to change phase between a crystalline phase and an amorphous phase. The amorphous phase is characterized by higher electrical resistivity than the crystalline phase. In operation of the phase change memory element, an electrical current pulse passed through the memory cell of the PCM can set or reset the resistivity phase of the phase change memory element (i.e., the electrical current pulse can be used to change the PCM between the amorphous phase and the crystalline phase).
The change from the amorphous phase to the crystalline phase, referred to herein as the SET operation, may be performed by applying an electrical pulse through the phase change material. In the electrical pulse, an initial peak current is followed by decreasing current over the duration of the pulse so that the phase change material slowly cools into the crystalline phase.
The change from the crystalline phase to the amorphous phase, referred to herein as the RESET operation, may be performed by applying a short high current electrical pulse through the phase change material to melt or break down the crystalline phase structure in the phase change material. Afterwards the phase change material cools quickly, quenching the phase change process and allowing at least a portion of the phase change material to stabilize in the amorphous phase.
PCM has the advantageous properties of scalability, dynamic random access memory (DRAM)-like operation and non-volatility, which make it a good candidate for storage class memory. However, PCM may be comprised of different combinations/compositions of germanium (Ge), antimony (Sb) and tellurium (Te), sometimes referred to as GST and may be used in different types of applications. These different combinations/compositions of GST and varying applications may require and/or perform optimally under different writing operations. For example, the timing, duration and levels of the signals required to perform the SET and RESET operations can vary depending upon the GST combinations/compositions of the PCM and depending upon the application/use of the PCM.
It is therefore desirable to provide a circuit that can adjustably write to a PCM based on the composition and the application/use of the PCM. Accordingly, proposed solutions are provided to implement an adjustable writing circuit for PCM, as well as multi-level cell (MLC) technology materials, other types of non-volatile memory, general memory and/or general semiconductor devices in order to improve the performance and/or reliability of the various types of memory (e.g., PCM) based on specific application/use of the memory and the type of the memory.